WindWaker

Perhaps interacting with other swords gave him more perspective. Before it only with other humans which might not have helped perhaps.

Hmm, I am not sure if the Sibling had any effect, as other deadeyes have not really recovered since the Sibling awakened. I think Sovereign is correct in that the effect is more due to the Ba-Ado-Mishram restoring some of the connection. Though I do not think either explains the change in Nightblood. I wonder if it has to do with bonds. Maybe Szeth bonded with Nightblood, giving him sentience? But then that would have happened with Vasher who is probably the being that held Nightblood the longest. Or maybe 2 individuals simultaneously saying the 5th oath gave him more sentience. Hmm. I think that may be the case, since Nightblood was created with Shardblade as inspiration. What I find interesting is that since Nightblood can steal pretty much any kind of investiture, keyed or not, anyone wielding Nightblood can potentially have the power of a Radiant.

Huh, that makes a lot of sense. So in this case, if Blackthorn was made self-aware, will it be a separate individual?

Spoiler Warning: Ending of Yumi and the Nightmare Painter In the ending of Yumi, we see her brought back by Painter. Technically though, she died all those years ago when the father machine started up, which means that Yumi herself was probably past to the beyond, leaving only a cognitive shadow that was maintained by the machine. When painter brought her back, her investiture materialized into a copy of Yumi with identical memory. I mention this because of the ending of WaT where we see Dalinar probably going to the beyond, effectively making him a 100% dead, but curiously, it is also mentioned that Blackthorn still lives on. Given that Dalinar has already Ascended, it’s possible that Blackthorn could exist as a Cognitive Shadow. Could this mean that, with sufficient Investiture, we might see a "copy" of Dalinar brought back, much like Yumi?

In WaT, we are told that large concentrations of Investiture left alone for extended periods can eventually develop sentience. We even see evidence of this with Honor, as Dalinar experiences its growing sentience when he touches it. Other than that, Nightblood exhibits qualities that resemble a Shard. With its Intent of "Destroy Evil," Nightblood never grasped the meaning behind this, and instead indiscriminately destroys anything it comes into contact with. However, in this book we see Nightblood beginning to evolve. It starts to display self-reflection, questioning its own understanding of what "evil" truly is. Additionally, Nightblood also seems to have a stronger sense of time, improved recall of those around it, and, most notably, the ability to resist the urge to consume Investiture. Why now though? Nightblood has existed for at least a couple of centuries at this point, so why now? My theory is that in killing Rayse and coming into direct contact with a Shard may have affected it. Looking forward, how do you think Nightblood might evolve further? I feel that it would stop stealing Investiture from its wielder, and perhaps even begin to grant Szeth access to Surges. Feeding off only from the investiture of those it killed. What do you guys think